Oceanus was an ancient Greek god. According to one version, he was born by the union of the primal gods Chaos and Gaea, sanctified by god Eros. Another version has it that he was one of the twelve Titans, thus a son of Gaea and Uranus.

Oceanus was married to his sister, Tethys, with whom he had numerous children, called Oceanids. These were the lesser gods and goddesses of the rivers, the sea, and the springs. In fact, Oceanus and Tethys were so fertile that the overproduction of the aqueous elements of nature would cause floods; so, they divorced to stop this from happening. The couple was not involved in the Titanomachy against Zeus, so the latter let them continue their reign in their watery kingdom.

In ancient Greek art, Oceanus was depicted having bull horns and the tail of a serpentine fish instead of legs. He was later considered as a simple sea god or the personification of the sea.